The present invention relates to axial flow compressors.
In axial flow compressors it is common practice to provide bleed offtakes in order to bleed working fluid from the compressor for various purposes. In axial flow compressors of gas turbine engines, working fluid is commonly bled from the axial flow compressor for cooling turbines, gearboxes, bearings or for supplying to an associated aircraft cabin air supply.
In axial flow compressors it is desirable to maintain a uniform small clearance between the rotor blade tips and the encircling static shroud, and to minimize the variations in the clearance between the rotor blade tips and the static shroud.
The use of bleed offtakes has resulted in a problem affecting the small clearance between the rotor blade tips and the static shroud. The bleeding of working fluid from the compressor has resulted in a local reduction of the clearance between the static shroud and the rotor blade tips in a circumferential half of the compressor in which the bleed offtake is positioned.